Centrifuge having frusto-conical screen with means to improve screen life



April 1967 D. E. HUMPHREY ETAL' CENTRIFUGE HAVING FRUSTO-CONICAL SCREEN WITH MEANS TO IMPROVE SCREEN LIFE Filed Nov. 13, 1964 INVENTION PRIOR ART Fig.3a

m nmR a m m m N A 0 WW w N A HDW n EAY NNR

AOR

EEE

DLP

United States Patent 3,315,810 CENTRIFUGE HAVING FRUSTO-CONICAL SCREEN WITH MEANS TO IMPROVE SCREEN LIFE Dean E. Humphrey, Lansdale, Leonard Shapiro, Upper Darby, and Perry W. Wilder, In, Philadelphia, Pa., assignors to Pennsalt Chemicals Corporation, Philadelphia, Pa., a corporation of Pennsylvania Filed Nov. 13, 1964, Ser. No. 411,039 3 Claims. (Cl. 210-369) This invention relates to centrifuges. More specifically this invention relates to screen centrifuges and provides means for dispersing the feed liquid to such centrifuges to minimize screen wear.

In prior screen centrifuges means have delivered feed to the center of the centrifuge. To accommodate high feed rates vanes mounted to rotate with the centrifuge screen have accelerated the feed and driven it outwardly. From the outer edges of these vanes feed has moved directly outward and has impinged upon the screen in localized zones. This has caused excessive wear in these zones.

The present invention has for an object the dispersal of the feed in such centrifuges so that the feed contacts the screen in broad areas rather than in localized zones.

It is a further object of this invention to provide means for deflecting the outwardly moving feed in such centrifuges in a direction which improves the efliciency of the centrifuge.

Further objects of the invention will be apparent from a reading of the following specification which includes drawings of structure embodying the invention. In the drawings:

FIGURE 1 is a fragmentary sectional view of an apparatus embodying the invention;

FIGURE 2 is an enlarged fragmentary sectional view taken on the line 2-2 of FIGURE 1; and

FIGURES 3a and 3b are fragmentary sectional views showing the action of feed engaging the screen in the prior art and under the invention respectively.

Briefly, the invention relates to a screen centrifuge having means mounting it for rotation about its axis and feed means disposed within the screen. The screen has a plurality of substantially radial feed-dispersing baflles which disperse the feed so that it impinges on the centrifuge screen in wide areas rather than in localized zones. A comparison of the action of the feed may be had by reference to FIGURES 3a and 3b. In these figures S indicates the screen, V the vanes and B the baffle in accordance with the present invention.

Referring more specifically to the drawings, an apparatus embodying the invention is shown in FIGURE 1 and is generally designated 10. It comprises a casing 12 in which is disposed a centrifuge screen assembly 14. The assembly 14 is mounted on the shaft 16 which is supported by means not shown. Drive means (also not shown) are provided. In the embodiment shown in FIG- URE 1 the assembly 14 includes a conventional frustoconical grating 18. The grating preferably has mounted against its inside surface a frusto-conical screen 20 of woven wire for strength and of perforate sheet metal 20a for smoothness. The ends of the screens 20 and 20a are clamped in position by clamping rings 22 and 24 which also comprise part of the screen assembly. The rear wall 26 of the screen assembly may carry target 26a.

Feed means comprise the stationary feed tube 28, disposed Within the screen assembly and mounted on the axis thereof. The feed means include the nozzle 28a which directs the feed along the axis to the small end of the screen assembly.

In operation the feed is deliquefied as it moves down the screen, the liquid passing through the screen assembly.

"ice

Partitions 30 in the casing divide the flow-through from the screen assembly into desired fractions. Finally the deliquefied feed moves over the clamping ring 22 for collection.

To assist in moving the feed outward to the surface of the screen 20a, a vaned weldment 32 is provided. In the embodiment shown it comprises the rear wall 26. Welded or otherwise secured to the rear wall are a plurality of substantially radially disposed imperforate vanes 36. Welded or otherwise secured to the opposite ends of the vanes is a ring 38. A leveling ring or darn may be secured to the ring 38 to assure uniformity of the feed flowing along the screen.

Focusing now on the specific area of the invention, a plurality of feed dispersing baflles 42 are provided. Each of these is formed on adjacent margins with reversely bent lips 44 and 46 which hook over and preferably comvpressively engage corresponding edges of the imperforate vanes 36. This attachment is enough to secure the dispersing baflles in position while the machine is at rest. It will be understood that when the centrifuge is in operation centrifugal force will enhance the attachment.

As shown in FIGURE 2 the distal or unattached edges of the baffles 42 are parallel to and proximate to screen 20 and are curved at 42a to disperse better the liquid feed. The direction in which the distal edges of the baflles are curved may be generally described as toward a direction parallel with the adjacent portion of the screen when viewed in a plane perpendicular to the axis of the screen. Additionally the dispersing bafiles are formed as shown in FIGURE 1 with diverting ribs 48. These ribs serve not only to strengthen the perforate baflies but also to deflect the outwardly moving feed liquid to a more upscreen position so that the impingement on the screen will be at a lesser radius than otherwise. (See arrows FIG. 1.)

The dispersing action of the baffles will be understood from reference to FIGURES 2 and 3b. As the feed moves outwardly alOng the substantially radially disposed baffles, it will engage the curved distal edges 36a of the baffies and will be deflected in advance of the rotation of the screen. Further, since the baffles are perforate some of the liquid and smaller solids of the feed will pass through the bafiles and swirl outwardly to engage the screen rearward of the battles. These combined actions have the overall effect of dispersing the feed so that the feed engages the screen in a wide area rather than in localized zones.

In a modification of the dispersing baflles of the invention the distal edges thereof are serrated or otherwise formed with irregular edges to assist in the scattering of feed particles over a wide area.

It should be understood that variations of the structure shown are possible within the scope of the invention. For instance, the invention is applicable to a cylindrical screen centrifuge. Further it may be applied to the conical screen of a pusher type centrifuge, an example of which is illustrated in US. Patent 3,136,722 which issued on an application by F. P. Gooch. The axis of any centrifuge embodying the invention may be either horizontal or vertical. The size of openings in the perforate baffle 42 may be varied in accordance with the best operation on the feed material involved.

Therefore, it is to be understood that the above particular description is by way of illustration and not of limitation, and that changes, omissions, additions, substitutions, and/or other modifications may be made without departing from the spirit of the invention. Accordingly, it is intended that the patent shall cover, by suitable expression in the claims, the various features of patentable novelty that reside in the invention.

We claim:

1. A screen centrifuge comprising a frusto-conical screen having an axis, means mounting the screen for rotation about t-he axis, feed means disposed within the screen and adapted to deliver feed to the smaller end of the screen, a plurality of substantially radially disposed feed-dispersing bafiles mounted within the screen for rotation therewith, the baffies being perforate and formed with flow-diverting ribs adapted to deflect the feed in a direction toward the smaller end of the frusto-conical screen and with outer edges curved toward a direction parallel with the adjacent portion of the screen when viewed in a plane perpendicular to the axis to enhance the dispersement of the feed, whereby the feed impinges the screen in Wide areas rather than in localized areas.

2. A screen centrifuge comprising a frusto-conical screen having an axis, means mounting the screen for rotation about the axis, feed means disposed within the screen and adapted to deliver feed to the smaller end of the screen, a plurality of imperforate radial vanes having edges adjacent the axis and mounted for rotation with the screen, a plurality of substantially radially disposed feed-dispersing baffles mounted within the screen for rotation therewith, the baffles being formed with perforations and with outer edges curved toward a direction parallel to the adjacent portion of the screen when viewed in a plane perpendicular to the axis of the screen, the baffles being secured on the vanes by means of reversely bent lips which hook over the said edges of the vanes.

3. A screen centrifuge comprising a frusto-conical screen having an axis, means mounting the screen for rotation about the axis, feed means disposed within the screen and adapted to deliver feed to the smaller end of the screen, a plurality of substantially radially disposed feed-dispersing baffles mounted within the screen for rotation therewith, the bafiies being flat and radial of the axis except for portions adjacent the outer edges which portions are curved toward a direction parallel to the adjacent portion of the screen but spaced therefrom when viewed ina plane perpendicular to the axis and the bafiles being perforate adjacent said edges whereby the feed moving outward along the baffles first impinges the screen in Wide areas ahead of and behind the screen area directly outward from the edges rather than in localized areas directly outward from the edges.

References Cited by the Examiner UNITED STATES PATENTS 1,902,982 3/1933 Abbott 210-380 X 2,312,829 3/1943 Bird et al 210-380 X 2,335,794 11/1943 Sanchez 210-377 X 2,370,353 2/1945 Howe 210-377 X 3,136,722 6/1964 Gooch 210-377 X FOREIGN PATENTS 22,674 10/ 1882 Germany.

REUBEN FRIEDMAN, Primary Examiner.

J. De CESARE, Assistant Examiner. 

1. A SCREEN CENTRIFUGE COMPRISING A FRUSTO-CONICAL SCREEN HAVING AN AXIS, MEANS MOUNTING THE SCREEN FOR ROTATION ABOUT THE AXIS, FEED MEANS DISPOSED WITHIN THE SCREEN AND ADAPTED TO DELIVER FEED TO THE SMALLER END OF THE SCREEN, A PLURALITY OF SUBSTANTIALLY RADIALLY DISPOSED FEED-DISPERSING BAFFLES MOUNTED WITHIN THE SCREEN FOR ROTATION THEREWITH, THE BAFFLES BEING PERFORATE AND FORMED WITH FLOW-DIVERTING RIBS ADAPTED TO DEFLECT THE FEED IN A DIRECTION TOWARD THE SMALLER END OF THE FRUSTO-CONICAL SCREEN AND WITH OUTER EDGES CURVED TOWARD A DIRECTION PARALLEL WITH THE ADJACENT PORTION OF THE SCREEN WHEN VIEWED IN A PLANE PERPENDICULAR TO THE AXIS TO ENHANCE THE DISPERSEMENT OF THE FEED, WHEREBY THE FEED IMPINGES THE SCREEN IN WIDE AREAS RATHER THAN IN LOCALIZED AREAS. 